A saw a great example of this earlier today. Darren Rowse asked his followers to define why they where following him. He wanted to make better use of his circles.

Going to do some work on my Circles later today. Could you leave a quick comment below and tell me why you're following me? Would love just a word or two of what kind of category you'd select if you could. For example: Blogging, social media, photography, Australia.

It is a good idea, but it just doesn't work. Here is what people answered (a small sample):

People do not fit into just one circle, and there is no way for you generalize your audience. We are not simpletons. Even if we mainly follow a brand or a person for a specific reason, we also want to be a part of the whole.

When Darren asked what category people belonged to, people basically said: "all of them." Yes, in his case there is a slight bias towards blogging, but he cannot rule out the other categories.

The only option Darren has now is to keep posting everything to everyone.

This is the real problem with Google+ Circles. It presumes that our connections are limited to specific topics. Work people are only interested in work. Bike people are only interested in bike updates. Friends are only interested in personal posts.

It is just not true.

Part of this problem will be solved when Google+ open up for brand pages. Then Darren (and the rest of us) can create brand profiles for Problogger, Digital Photography School, or FeelGooder. This way he can create the right of level focus and people can decide what channels they want to follow.

The same is true for other brands on Facebook or Twitter. We know from countless studies that 40-something percent follow because of offers and discounts. And while that might be the main reason they follow, it is not the only reason.

If you are a big brand, like Walmart or Best Buy, it might be useful to create a channel for just discounts. It would probably make you a lot of money. But if you are a smaller brand mixing your communications means that you can expand how people perceive you.